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nilfs2: avoid rec_len overflow with 64KB block size
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With 64KB blocksize, a directory entry can have size 64KB which does
not fit into 16 bits we have for entry length.  So this patch stores
0xffff instead and converts value when read from / written to disk.

Nilfs derives its directory implementation from ext2 filesystem, and
this draws upon the corresponding change on ext2.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
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Ryusuke Konishi committed Jul 25, 2010
1 parent c28e69d commit 6cda9fa
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Showing 2 changed files with 32 additions and 12 deletions.
26 changes: 14 additions & 12 deletions fs/nilfs2/dir.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -141,7 +141,7 @@ static void nilfs_check_page(struct page *page)
}
for (offs = 0; offs <= limit - NILFS_DIR_REC_LEN(1); offs += rec_len) {
p = (struct nilfs_dir_entry *)(kaddr + offs);
rec_len = le16_to_cpu(p->rec_len);
rec_len = nilfs_rec_len_from_disk(p->rec_len);

if (rec_len < NILFS_DIR_REC_LEN(1))
goto Eshort;
Expand Down Expand Up @@ -235,7 +235,8 @@ nilfs_match(int len, const unsigned char *name, struct nilfs_dir_entry *de)
*/
static struct nilfs_dir_entry *nilfs_next_entry(struct nilfs_dir_entry *p)
{
return (struct nilfs_dir_entry *)((char *)p + le16_to_cpu(p->rec_len));
return (struct nilfs_dir_entry *)((char *)p +
nilfs_rec_len_from_disk(p->rec_len));
}

static unsigned char
Expand Down Expand Up @@ -326,7 +327,7 @@ static int nilfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
goto success;
}
}
filp->f_pos += le16_to_cpu(de->rec_len);
filp->f_pos += nilfs_rec_len_from_disk(de->rec_len);
}
nilfs_put_page(page);
}
Expand Down Expand Up @@ -441,7 +442,7 @@ void nilfs_set_link(struct inode *dir, struct nilfs_dir_entry *de,
struct page *page, struct inode *inode)
{
unsigned from = (char *) de - (char *) page_address(page);
unsigned to = from + le16_to_cpu(de->rec_len);
unsigned to = from + nilfs_rec_len_from_disk(de->rec_len);
struct address_space *mapping = page->mapping;
int err;

Expand Down Expand Up @@ -497,7 +498,7 @@ int nilfs_add_link(struct dentry *dentry, struct inode *inode)
/* We hit i_size */
name_len = 0;
rec_len = chunk_size;
de->rec_len = cpu_to_le16(chunk_size);
de->rec_len = nilfs_rec_len_to_disk(chunk_size);
de->inode = 0;
goto got_it;
}
Expand All @@ -511,7 +512,7 @@ int nilfs_add_link(struct dentry *dentry, struct inode *inode)
if (nilfs_match(namelen, name, de))
goto out_unlock;
name_len = NILFS_DIR_REC_LEN(de->name_len);
rec_len = le16_to_cpu(de->rec_len);
rec_len = nilfs_rec_len_from_disk(de->rec_len);
if (!de->inode && rec_len >= reclen)
goto got_it;
if (rec_len >= name_len + reclen)
Expand All @@ -534,8 +535,8 @@ int nilfs_add_link(struct dentry *dentry, struct inode *inode)
struct nilfs_dir_entry *de1;

de1 = (struct nilfs_dir_entry *)((char *)de + name_len);
de1->rec_len = cpu_to_le16(rec_len - name_len);
de->rec_len = cpu_to_le16(name_len);
de1->rec_len = nilfs_rec_len_to_disk(rec_len - name_len);
de->rec_len = nilfs_rec_len_to_disk(name_len);
de = de1;
}
de->name_len = namelen;
Expand Down Expand Up @@ -566,7 +567,8 @@ int nilfs_delete_entry(struct nilfs_dir_entry *dir, struct page *page)
struct inode *inode = mapping->host;
char *kaddr = page_address(page);
unsigned from = ((char *)dir - kaddr) & ~(nilfs_chunk_size(inode) - 1);
unsigned to = ((char *)dir - kaddr) + le16_to_cpu(dir->rec_len);
unsigned to = ((char *)dir - kaddr) +
nilfs_rec_len_from_disk(dir->rec_len);
struct nilfs_dir_entry *pde = NULL;
struct nilfs_dir_entry *de = (struct nilfs_dir_entry *)(kaddr + from);
int err;
Expand All @@ -587,7 +589,7 @@ int nilfs_delete_entry(struct nilfs_dir_entry *dir, struct page *page)
err = nilfs_prepare_chunk(page, mapping, from, to);
BUG_ON(err);
if (pde)
pde->rec_len = cpu_to_le16(to - from);
pde->rec_len = nilfs_rec_len_to_disk(to - from);
dir->inode = 0;
nilfs_commit_chunk(page, mapping, from, to);
inode->i_ctime = inode->i_mtime = CURRENT_TIME;
Expand Down Expand Up @@ -621,14 +623,14 @@ int nilfs_make_empty(struct inode *inode, struct inode *parent)
memset(kaddr, 0, chunk_size);
de = (struct nilfs_dir_entry *)kaddr;
de->name_len = 1;
de->rec_len = cpu_to_le16(NILFS_DIR_REC_LEN(1));
de->rec_len = nilfs_rec_len_to_disk(NILFS_DIR_REC_LEN(1));
memcpy(de->name, ".\0\0", 4);
de->inode = cpu_to_le64(inode->i_ino);
nilfs_set_de_type(de, inode);

de = (struct nilfs_dir_entry *)(kaddr + NILFS_DIR_REC_LEN(1));
de->name_len = 2;
de->rec_len = cpu_to_le16(chunk_size - NILFS_DIR_REC_LEN(1));
de->rec_len = nilfs_rec_len_to_disk(chunk_size - NILFS_DIR_REC_LEN(1));
de->inode = cpu_to_le64(parent->i_ino);
memcpy(de->name, "..\0", 4);
nilfs_set_de_type(de, inode);
Expand Down
18 changes: 18 additions & 0 deletions include/linux/nilfs2_fs.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -326,7 +326,25 @@ enum {
#define NILFS_DIR_ROUND (NILFS_DIR_PAD - 1)
#define NILFS_DIR_REC_LEN(name_len) (((name_len) + 12 + NILFS_DIR_ROUND) & \
~NILFS_DIR_ROUND)
#define NILFS_MAX_REC_LEN ((1<<16)-1)

static inline unsigned nilfs_rec_len_from_disk(__le16 dlen)
{
unsigned len = le16_to_cpu(dlen);

if (len == NILFS_MAX_REC_LEN)
return 1 << 16;
return len;
}

static inline __le16 nilfs_rec_len_to_disk(unsigned len)
{
if (len == (1 << 16))
return cpu_to_le16(NILFS_MAX_REC_LEN);
else if (len > (1 << 16))
BUG();
return cpu_to_le16(len);
}

/**
* struct nilfs_finfo - file information
Expand Down

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